Signalling device



S35i/WCM Dec. 18, 1956 L. H. JAMES 2,774,324

SIGNALLING DEVICE Filed April l, 1953 J0 ,iw 791.

im, z oo-o'o'fooooooooo l' I ooooooooooooo oooooooooooo-O JQM/ZZZC//QW,ooooooooooooo y oo Q ooo oQQQOoo fEfQZW/Q///VZ nited States gPatentSIGNALLING DEVICE Lawrence H. llames, Glen Ellyn, lll.

Application April 1, 1953, Serial No. 346,138

11 Claims. (Cl. 116-109) This invention relates to a device whichdelivers a signal when the boiling liquid level in a heated containerfalls below a predetermined level by utilizing the combined effect ofthe lower temperature of the area immediately above the surface of theboiling liquid and the sudden drop in temperature of the hot wettedsurface upon evaporation of the last liquid therefrom.

In the boiling of any liquid in a container, substances dissolved ordispersed within the liquid may be injured if the heat to theliquid-containing vessel is continued after evaporation of apredetermined minimal amount of liquid. It is therefore desirable tohave an audible signal indicating when the boiling liquid reaches apredetermined level, particularly when one is unable to see the liquidin the container. In this way charring and possible warpage of thecontainer may be prevented.

The present invention provides a simple, economical device by which asignal is delivered whenever a wettable liquid in a container reaches apredetermined level. This signal can readily be utilized toautomatically turn olf a heat source to the container.

Essentially, the device is to be used with a liquid heating vesselcontaining a wettable liquid and comprises a temperature responsivemeans adapted to be immersed in the liquid at a predetermined level, andmeans associated with the temperature sensitive means to actuate -asignalling device upon an impulse resulting from a decrease intemperature of the top surface of the temperature responsive means uponthe combined effect of exposure of the temperature responsive means tothe area immediately adjacent the top surface of the boiling liquid andthe consequent evaporation of the last liquid from the top exposedsurface of the temperature responsive means.

An embodiment of a preferred form of this invention is illustrated inthe accompanying drawings, in which:

Fig. l is an elevational view partially in section of the apparatus;

Fig. 2 is a section View, taken along line 2-2 in Fig. l;

Fig. 3 is an enlarged elevation view of the gripping elements shown inFig. l;

Fig. 4 is a plan view of the components shown in Fig. 3;

Fig. 5 is an end view, taken along line 5--5, of the temperaturesensitive element shown in Fig. l; and

Fig. 6 is a plan View of the temperature sensitive element.

The temperature sensitive element 10, here shown as a bulb, has achamber 11, with connection 12. As best seen in Fig. 5, a perforatedbaille 13 is removably crimped to the protruding top surface of the bulbto faciLtate cleaning. The bulb has a generally rectangular crosssection in the preferred form for ready location in or adjacent thebottom of a liquid containing vessel, but ma)l have other transversecross-sectional shapes. It is desirable to have a comparatively largetop surface area. Ordinarily the bulb is constructed of metal, but anyheat conducting material may be used.

As best seen in Fig. 1, the signalling device 14 is com- ICC posed of acylindrically-shaped lcompartment 15 having a top plate 16 and a baseplate 17. The inner surface of the base plate is hollowed out providingan annular ring portion 18 about the side walls of the compartment. Apressure sensitive expansible element 19, here shown as a resilientdiaphragm, is mounted atop the annular ring portion 18 and secured inplace against an annular ring 2l) integral with the compartment innerwall. The hollowed out portion of the base plate 17 together with thediaphragm 19 form a chamber 21.

The base plate 17 contains a tapped hole 21a leading into chamber 21. Aflexible conduit 22 is connected to this hole, leading to bulb 10 toform a sealed system comprising the chamber 21, the conduit 22 and thebulb 10. The connection 21a of the chamber and connection 12 of the bulbare air-tight. The system is lled with a compressible fluid, such asalcohol. Any liquid may be employed that has a boiling pointsubstantially lower than that of the boiling liquid to be used in thevessel.

A rod 23 is mounted centrally on and extends outwardly from thediaphragm, thus being positioned axially in the cylindrically-shapedcompartment 15. Slidingly mounted on rod 23 are gripping elements 24 and25. As seen in Fig. 3, these elements are pivotally attached to eachother by means of wires 26 and 27. 'I'he planar opposing faces ofgripping elements are provided with grooves 28 and 29, to permitinsertion of rod 23 between them when the opposing faces are in closeproximity to each other. As seen in Fig. 4, the grooves are sectors ofcircles having radii somewhat greater than the radius of rod 23. Tocause the planar faces of the gripping elements to remain in closeproximity, wire 26 is here shown as a coiled tension spring pivotablymounted on pin 26a, gripping element 25 and pivotably secured togripping elements 24 and 25.

Circular plate 30 extends across the compartment 15, being positionedabove the diaphragm 19 by means of support members 31. Plate 30 istapped at its center to permit passage of rod 23 therethrough and toprovide a bearing for reset shaft 49. Trigger arm 32 is attached to `andextends radially from gripping element 25 and extends upwardly through aslot 33 in plate 30. Secured to plate 30 and trigger arm 32 is tensionspring 34. Bolt 35 is threaded into the upper face of element 25. Bolt36 is screwed into gripping element 24 and extends through elongatedopening 37 in plate 30.

Bell ringer lever 38 is pivotably mounted on pin 39 which is mounted onplate 30. As best seen in Fig. 2, the bell ringer lever 38 tends topivot counterclockwise about pin 39 under the inlluence of tensionspring 40 except for the holding action of trigger arm 32. At one end,spring 40 is secured to plate 30 and at the other to the operating armof bell ringer lever 38 at a point between pivot pin 39 and triggerpoint 41. Bell ringer hammer 42 is equipped with an elongated slot forslide mounting at the end of the power arm of bell ringer lever 38.

Top plate 16 is bolted to signalling device 14 and is equipped withdependent female threaded bosses 43 for receiving bolts 44, thussuspending bell 45. Top plate 16 is perforated to permit emission ofsound from bell 45. When trigger arm 32 is disengaged at trigger point41 from the bell ringer lever 38, the lever rotates under the influenceof spring 40 to cause bell ringer hammer 42 to contact bell 45. Therotating motion of lever 38 is stopped when the operating arm contactsstopping pin 46 which is mounted on plate 30. The slide mounting featureof bell ringer hammer 42 causes the hammer to reciprocate, setting up atrain of rings of diminishing intensity.

Top plate 16 and bell 45 are equipped with bearing openings 47 and 48 tocarry reset shaft 49 with reset knob 50 aixed thereto external to thesignalling device 14. Reset shaft 49 is mounted axially in cylindricalsignalling device 14 and is cored at the end opposite the knob to permitreception of rod 23. Afxed to the end of the hollow portion of resetshaft 49 are cams 51 and 52. Spring washer 53 is attached to reset shaft49 at a point immediately external to bearing opening 47 in top plate16. Spring washer 53 is compressed and secured in place by tapped washerplate 54. Washer plate 54 is bolted to top plate 16 by bolts 55.

In the normal use of this invention, the temperature sensitive elementwill be positioned at a predetermined level in a heating vesselcontaining a wettable liquid so as to be immersed therein. The baille 13permits the liquid lto contact the top surface of element 10 butprevents contact of any solids dispersed in the liquid from contactingthat surface. As heat is applied to the vessel to boil the liquid, thecompressible fluid within the temperature responsive system expands,causing ilexible diaphragm 19 to expand.

As the diaphragm expands, rod 23 moves upwardly a corresponding distancein the signalling device 14. Gripping element 25, which is slidablymounted on rod 23, will accompany the upward motion of the rod untilbolt 35 engages plate 30. Further upward movement of rod 23 inducesgripping element 24 to pivot about element 25, permitting freer movementof rod 23 into the recessed opening in reset shaft 49. Such expansioncontinues until the boiling point of the liquid is reached.

Upon exposure of bulb 10 above the top surface of the boiling liquid,the temperature of the compressible fluid drops due to the combinedeffect of being exposed to the lowe-r temperature area immediatelyadjacent the top surface of the boiling liquid and the evaporation ofthe last liquid from the exposed surface of the bulb. This causescompression of the compressible fluid and a collapse of diaphragm 19.Rod 23 then moves downwardly at the same time. It is this downwardmovement that is utilized to deliver a warning signal in the picturedembodiment. Other means readily apparent to one skilled in the art maybe employed in combination with the temperature responsive system to usethis collapsing elect to deliver a signal. The downward movement of rod23 causes both gripping elements 24 and 25, to accompany it. The slightdownward movement of element 24 causes trigger arm 32 to becomedisengaged from the bell ringer lever 38. This disengagement causes thebell 45 to be struck a number of blows by bell ringer hammer 42.

To reset the apparatus, knob 50 is turned, rotating cams 51 and 52 whichcontact bolt 36 and bell ringer lever 38. The Contact against bolt 36separates the gripping elements 24 and 25 permitting rod 23 to return toits equilibrium position. It further permits element 2S to return to itsequilibrium position whereby trigger arm 32 holds bell ringer lever 38in a cocked position. Uridesirable rotation of cams 51 and 52 isprevented by the holding action of springer washer 53 on reset shaft 49.

While I have shown and described certain embodiments of my invention, itis to be understood that it is capable of many modifications. Changes,therefore, in the construction and arrangement may be made withoutdeparting from the spirit and scope of the invention as disclosed in-the appended claims.

I claim:

1. In combination with a liquid heating vessel adapted to boil awettable liquid, a wettable liquid contained therein, temperatureresponsive means operatively associated with said vessel, and actuatingmeans responsive to said temperature responsive means upon exposure ofsaid temperature responsive means, after immersion in the wettableliquid, to the area immediately adjacent the top surface of boilingwettable liquid and the drop in temperature of the surface of thetemperature responsive said actuating means serving to actuate indicatormeans which serves to indicate when the liquid level of boiling wettableliquid falls below a predetermined level.

2. In combination with a liquid heating vessel adapted to boil awettable liquid, a wettable liquid contained therein, temperatureresponsive means operatively associated with said vessel, actuatingmeans responsive to said temperature responsive means upon exposure ofsaid temperature responsive means, after immersion in the wettableliquid, to the area immediately adjacent the top surface of boilingwettable liquid and the -drop in temperature of the surface of thetemperature responsive means upon evaporation of the last liquidtherefrom, and indicator means which is responsive to and actuated bysaid actuating means, said indicator means serving to indicate when theliquid level of boiling wettable liquid falls below a predeterminedlevel.

3. In combination with a liquid heating vessel adapted to =boil awettable liquid, a wettable liquid contained therein, temperatureresponsive means operatively associated with said vessel, saidtemperature responsive means containing a compressible fluid, landactuating means responsive to a decrease in pressure of saidcompressible fluid resulting from exposure of said temperatureresponsive means, after immersion in lthe wettable liquid, to the areaimmediately adjacent the top surface of boiling wettable liquid and thedrop in temperature of the surface of the temperature responsive meansupon evaporartion of the last liquid therefrom, said actuating meansserving to actuate indicator means which serves to indicate when theliquid level of Iboiling wettable liquid falls below a predeterminedlevel.

4. In combination with a liquid heating vessel adapted to boil awettable liquid, a wettable liquid contained therein, temperatureresponsive means operatively associated with said vessel, saidtemperature responsive means containing a compressible fluid, actuatingmeans responsive to a decrease in pressure -of said compressible fluidresulting from exposure of said temperature responsive means, afterimmersion in the wettable liquid, to ythe area immediately adjacent thetop surface of boiling wettable liquid and the drop in temperature ofthe surface of the temperature responsive means upon evaporation of thelast liquid therefrom, and indicator means which is responsive to andactuated yby said actuating means which serves to indicate when theliquid level of boiling wettable liquid falls below a predeterminedlevel.

5. The device as set forth in claim 4 wherein said in dicator meanscomprises audible signal means which produces an audible signal uponlbeing actuated by said actuating means.

6. In combination with a liquid heating vessel adapted to boil awettable liquid contained therein, a sealed system having chamber means,pressure-sensitive ilexible means dening at least .a portion of saidchamber, a bulb adapted for immersion in the rwettable liquid at apredetermined level constructed of heat conduc-ting material, said bulbbeing iilled with compressible fluid, conduit means operativelyconnecting the Ibulb to said chamber, said conduit means being free of amovable, actuating portion of said pressure-sensitive means, saidpressuresensitive means lbeing adapted to be actuated by being ilexedoutwardly when the pressure and temperature of the compressible fluidare increased, said pressure-sensitive means Ibeing capable of beingflexed inwardly, from said outward position, resulting from a pressuredrop of the compressible fluid caused -by exposure of the bulb to thearea immediately adjacent the top surface of |the boiling wettableliquid.

7. The device set forth in claim 6 wherein the pressure-sensitive meansis operatively connected to indicator means so that actuation of thepressure-sensitive means, resulting from said pressure drop lof saidcompressible means upon evaporation of the last liquid therefrom,Ifluid, actuates said indicator means when the liquid level of boiling-wettable liquid -falls Ibelow la predetermined level.

8. The device set forth in claim 6 wherein the pressure-sensitive meansis operatively connected to audible signal means which produces an.audible signal upon actuation of the pressure-sensitive means, saidlast-mentioned actuation resulting from said pressure drop of saidcompressible fluid.

9. A sealed system adapted to be used in combination with a liquidheating vessel, said vessel being capable of being used lto boil awettable liquid comprising: cham- 'ber means, pressure-sensitiveflexible means `defining at least a portion of said chamber, a bulbadapted to be immersed in wettable liquid ata predetermined levelconstructed of heat conducting material, said bulb being filled withcompressible iluid, conduit means operatively connecting lthe Ibulb tosaid chamber, said conduit means being free of a movable, actua-tingportion of said pressure-sensitive means, said pressure-sensitive meansbeing adapted to -be actuated by being flexed outwardly when thepressure and temperature of the compressible fluid are increased, saidpressure-sensitive means being capable of being ex-ed inwardly, Afromsaid outward position, resulting from a pressure drop of thecompressible fluid caused =by exposure of Ithe bulb to the :areaimmediately adjacent the top surface of the boiling wettable liquid.

10. The device set `forth in claim 9 wherein the pressure-sensitivemeans is operatively connect-ed `to audible signal means which producesan audible signal upon actuation of the pressure-sensitive means, saidlast-mentioned actuation resulting from said pressure drop yof saidcompressible fluid.

lll. The sealed system set forth in -claim 9 wherein thepressure-sensitive means is operatively connected to temperature controlsignalling means so that a pressure drop of said compressible iluid will`cause said pressure-sensitive means to activate said signalling means.

References Cited in the le of this patent UNITED STATES PATENTS 62,37'1Savage Feb. 26, 1867 980,831 Peterson `lan. 3, 1911 992,145 Banhar-t May16, 1911 997,987 Frey July 18, 1911 2,546,608 Melick Mar. 27, 19512,632,419 Topping Mar. 24, 1953

